1. Field of the Invention
At least one embodiment of the invention relates to a permanently or temporarily implantable device having an longitudinally extended electrical conductor.
2. Description of the Related Art
Such devices, for example, electrode leads for electrostimulation, have the disadvantage that the electrical conductors thereof can heat up in an MRI machine because the alternating magnetic fields prevailing in the MRI machine induce substantial electrical currents in the electrical conductor. For this reason, heart pacemaker patients today usually cannot be examined in an MRI machine or can be examined only to a limited extent.
Implantable heart pacemakers or defibrillators typically have at least one stimulation electrode lead, wherein said electrode lead has a standardized electrical connection on its proximal end, said end being provided for connection to the heart pacemaker or defibrillator, and said electrode lead has one or more electrode poles on its distal end, said distal end being provided for placement in the heart. Such an electrode pole serves to deliver electrical pulses to the (myocardial) tissue of the heart or for sensing electrical fields to be able to sense an activity of a heart as part of so-called sensing. Electrode poles are typically provided in the form of a ring around the electrode lead, having an electrically conductive surface or in the form of a point electrode or tip electrode on the distal end of the electrode lead. The electrode poles are electrically connected to contacts of the electrical connection of the electrode lead at the proximal end thereof by way of one or more electrical conductors. The electrode leads on their proximal end and the electrode poles on the distal end of the electrode lead run between the contacts of the electrical connection, these electrical conductors electrically connecting one or more of the electrode poles to one or more of the contacts. These electrical conductors may be used to transmit stimulation pulses to the electrode poles and also to transmit electrical signals picked up by the electrode poles to the proximal end of the electrode lead. In the following description, these electrical conductors are referred to as functional leads in the course of the following description. Such functional leads are electrical conductors, which are necessary for the functions of the respective electrode lead and as such are exposed to the risk that electrical currents may be induced in them by external alternating magnetic fields, but these electrical currents may result in unwanted heating of the functional leads or of the electrode poles connected to them, for example.